Boat steering mechanism



Nov. 18, 1941. A. g. DOW 2,263,529

BQAT STEERING MECHANI SM Filed April 21, 1939 11v VENTOR I A/a zn 25. 00W 4* 5 v A TTORNEY Patented Nov. 18, 1941 UNITED BOAT STEERING MECHANISM Alden B. Dow, Midland, Mich. Application April 21, 1939, Serial no. 269,278

1 Claim.

The present invention relates to steering mechanisms for self-propelled water craft, particularly inland water craft of small or moderate size.

It is a primary object; of the invention to provide a steering apparatus for self-propelled water craft by means of which the same can be turned on a relatively short radius. To this end, I have now invented a steering mechanism for use on inland water craft which comprises rudders extending at least partially below the waterline of such craft, mounted at substantially the longitudinal center of gravity on each side of the craft, and means to rotate said rudders simultaneously to vary their angle of incidence in the same direction.

The invention, then consists of the means hereinafter fully described and particularly pointed out in the claim, the annexed drawing, and the following description, setting forth in detail certain means for carrying out the invention, such disclosed means illustrating, however, but one of the various ways in which the principle of the invention may be used.

In said annexed drawing:

. Figure 1 is a sideelevation of a water craft illustrating my invention.

Figure 2 is a typical section taken on the line 22 of Figure 1, looking toward the bow.

Figure 3 is an enlarged part section from Figure 2.

Figure 4 is a side elevation of Figure 3.

Figure 5 is an enlarged part elevation from Figure 2.

Referring now to the drawing, Figure 1 shows a side elevation of the hull 6 of an ordinary inboard motor boat. A rudder I2 is mounted on each side of said hull 6 at approximately the longitudinal center of gravity thereof so as to be at least partially submerged in water when .the boat is in motion. The position of the steering wheel I and steering post, with relation to the rudder I2, is shown in dotted lines.

Referring now to Figure 2, the sides 8 and 8' of the boat hull 6 are each provided on the water side with a plate 9 and 9' bearing bosses I and Ill, through which extend shafts II and II carrying rudders I2 and I2 of discoidal shape. Each of the sides 8 and 8' is provided on the inner side thereof with a plate I3 and I3 which carries a boss I 4 and I4 and a blind boss I and I5. Each plate I3 and I3 is so placed on the inner side of the sides 8 and 8' so that the shafts II and II extending through the bosses In and I0 also extend through the bosses I4 and I4. The shafts II and II are each provided, inside the boat hull, with a bevel gear I5 and [6; these bevel gears mesh with bevel gears IT and I1 carriedon the horizontal shafts I8 and I8, of which the blind bosses I5 and I5 carry one end and the other end projects through the bracket bearings I9 and I9. Each shaft I8 and I8" carries on the end thereof which projects through the said-bracket bearing a bevel gear 20 and 29 adapted to mesh with the bevel gear 2I mounted on the end of the steering wheel post 22 (for which no support is here shown). The horizontal shafts I8 and I8 are parallel with the bottom of the hull 6. The shafts II and II" carrying the rudder discs are preferably mounted at an angle of about 45 to the horizontal. The rudder discs I2 and I2" aremounted on the ends of the shafts and H, so that, when in their normal position, their major axis is substantially vertical.

Referring to Figure 3', this figure shows, in dotted lines, the position A of the rudder disc I2 which would be produced by rotating the steering-wheel 1 (shown in Figure l) in a counterclockwise direction. Thus, when the steering Wheel is turned to the left, the leading edge of the rudder [2 will be moved away from the side 8 of the boat hull, varying the angle of incidence of the rudder, and causing the hull to veer toward the left. The position B of the rudder I2 will be produced by rotating the steering wheel in a clockwise direction, thus causing the leading edge of the rudder disc I2 to be moved toward the side 8 and thereby cause the hull to veer toward the right.

Referring now to Figure 4, which is a side elevation of the part-section shown in Figure 3, said figure shows the external plate 9 on the side 8 as having a tear drop shape. The rudder disc I2 is attached to the shaft II (shown in dotted lines) on the horizontal center line of the rudder disc I2 at a point slightly forward of the vertical center line of said rudder.

Referring now to Figure 5, this enlarged part elevation shows particularly the steering post gear arrangement, which has been described with reference to Figure 2.

In operation, the vertical planes of the two rudders remain substantially parallel at all times. When the steering wheel is turned to impart a change of direction to the boat, the rudders revolve in a manner such that horizontal filaments through the rudders form an angle with the longitudinal axis of the boat hull. The vertical elevation of the rearmost point of the line of intersection of any vertical plane parallel to the longitudinal axis of the hull with the rudders is greater than the vertical elevation of the foremost point of each such line of intersection. As a result of the angle formed between the horizontal filaments of said rudders and the longitudinal axis of said hull when said rudders are rotated, a turning-moment in the plane of the water is applied to the hull through the couple resulting from the force of reaction of the rudders on the water, acting through the momentarm represented by the horizontal distances of said rudders from the center of gravity of the craft. moment, in the vertical transverse plane of the hull, results from the operation of the rudders which moment is opposite to and greater than the turning-moment, or wrecking moment, resulting from centrifugal force. The aforementioned righting-moment is afforded by the vertical downward force excited on the rudders by the water as a result of the fact that the leading edges of the rudder surfaces are at a lower elevation than are the corresponding trailing edges, thereby creating a scoop effect. Thus a downward reaction is produced which acts through the moment-arm represented by the distance from the rudders to the center of gravity of the hull. The downward reaction on the rudder nearer the center about which the hull is turning is much greater than that on the outer rudder due to the fact that its leading edge is turned away from the hull and its trailing edge is turned toward said hull, creating a funnel effect whereby a much greater mass of water is reacted upon than is the case with the opposite rudder, the leading edge of which is turned toward the hull, and is thus brought in contact with a smaller mass of water.

As is well known, a boat traveling in a straight line can be caused to turn by depressing one side of said boat as by shifting the passengers, and the depressed side will be nearer the center of turning than the higher side. This invention provides means of automatically depressing the inner side of the hull in the turns. By thus automatically depressing the sides of the hull nearer the center about which a turn is being made, the hull is caused to make a banked turn A further turning-moment or righting against an inclined wall of water, thereby greatly decreasing the radius of turning and eliminating the tendency to overturn resulting from centrifugal force, which is commonly encountered when turns of a short radius are attempted.

Under these conditions the rudder on the side of the boat away from the center of turning tends to'-lift that side of the craft out of the water, thus assisting the making of short-radius turns.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the mechanism herein disclosed, provided the means stated by the following claim or the equivalent of such stated means be employed.

I therefore particularly point out and distinctly claim as my invention:

A steering mechanism for self propelled water craft comprising; a bracket housing on the craft floor substantially at the longitudinal center of gravity of the craft and equidistant the sides of the craft; a steering post projecting into said housing; a bevel gear on said post in said housing; twin horizontal shafts parallel to the bottom of said craft, projecting from said housing towards the side of said craft; a bevel gear on each of said twin shafts in said housing, adapted to engage said bevel gear on said steering post; a bevel gear on each of said shafts near the sides of said craft; a plate on each of the sides of said craft, each plate carrying a blind boss for receiving the end of one of said twin shafts, and a bearing boss on each of said plates; twin rudder shafts each extending through one of said bearing bosses, and carrying a bevel gear adapted to engage with the corresponding bevel gear on one Of said twin horizontal shafts, and each being mounted at an angle of about degrees to the horizontal; a plate on the water side of each of the sides of the craft, each plate carrying a bearing boss for one of said twin rudder shafts; and twin vertical discoidal rudders, one being carried on the water end of each of said twin inclined rudder shafts in such position that it extends at least partially below the water line of said craft when the craft is in motion.

ALDEN B. DOW. 

